Gill wrote
So are you saying that you use nothing other than natural systems to
filter the pond? Or do you have a filter in addition to the plants? Or
do you use the waterfall as a veggie filter?

Usually the waterfall if full of watercress. But if you look at the
slideshow you'll see it is clear this year as DH wanted to see if it
could do the job alone and he likes to see the
waterfall. The hornwort took off and the pond is full of it and I'm
wondering if it is a direct result and is taking over the job as
veggie filter?
The pond is 3,000+ gallons and is lightly stocked.The hornwort is
hiding the fish much of the day and that's probably a good thing as a
heron was stopping by once in a while.

k :-)
http://tinyurl.com/6bguh ~ new pond keeper info
http://tinyurl.com/yp64db ~ slide show of pond